The Lumia 630 was developed under the name "Moneypenny". It is possible the Lumia 635 was the device codenamed "Phantom", or it may just be another variant of Moneypenny given its high level of similarity other than in cellular modem choice.

The Lumia 630's screen and camera (no flash?) leave plenty to be desired, but that's hardly a surprise. At the $160 price point, this is still a pretty impressive device. This is also the first time that a Nokia Lumia had dual-SIM capability, an increasingly vital feature for regions like Europe or South America, where traveling 20 miles from your home might take you into a different country served by different carriers.

The Lumia 630 is Nokia's first dual-sim capable Windows Phone device.

It looks great, with plenty of customization/variety to adjust to your personal tastes. And the fact that microSD is on this phone makes it more attractive than the richer-featured Lumia 930 in some regards.

The Nokia Lumia 630

The phones pack key improvements from the Windows Phone 8.1 update, including the Cortana voice assistance, Swype-style typing, and an Action Center.

The new phones include the Cortana voice assistant.

Nokia/Microsoft has a strong challenger to low-end Android smartphones in the Lumia 630, and it would not be surprising to see it be a key driver of sales.

Swype-style typing is found on the Lumia 630.

The Lumia 635 is nearly identical to the Lumia 630, adds a shinier finish and has "a unique dual-layered, luminous tonal surround that glimmers and glows" (aka a speaker upgrade). It also adds on LTE support.

The Lumia 635 adds gloss to the body and includes LTE.

Both phones feature SensorCore, a firmware/hardware solution that offers the ability to wake the phone or receive input under certain conditions, while saving battery life.

The Lumia 635, in orange.

The Lumia 635 will be the first of the Windows Phone 8.1 devices announced today to be available in the U.S. It will be "broadly available, including in the U.S. starting this summer". It will retail for $189 USD -- $20 USD more than the base Lumia 630, on account of the LTE and the more refined finish. AT&T, Inc. (T) and Deutsche Telekom AG's (ETR:DTE) unified MetroPCS and T-Mobile USA brands have all announced they will sell the Lumia 635 this summer.